Bag top closing and sealing machine



April 11, 1961 F. L. HOPKINS ETAL 2,978,852?

BAG TOP CLOSING AND SEALING MACHINE Filed March '7, 1960 5 Sheets-Sheet1 8Q JNVENTORS FRANKLHOPK/NS y RICHARD h. A YRES 7 ATTORNEYS April 11,1961 F. L. HOPKINS ET AL 2,978,852

BAG TOP CLOSING AND SEALING MACHINE 5 Sheets-Sheet 2 Filed March '7,1960 April 1951 F. L. HOPKINS ETAL 2,978,852

BAG TOP CLOSING AND SEALING MACHINE Filed March 7, 1960 5 Sheets-Sheet 3FIG. 4

INVENTORS FRA NK 1.. HOPKINS 1 By RICHARD h. AYREJ (47TORNEYJ TRA VELApril 11, 1961 F. HOPKINS ETAL 2,978,852

BAG TOP CLOSING AND SEALING MACHINE Filed March 7, 1960 5 Sheets-Sheet 4-I l 4 4 85 I I] 4 l! 1 -93 I] I 92 u l INVENTORS FRANK L HOPKINS yRICHARD /1./4 YRES A 7- TORNE Y6" April 11, 1961 F. HOPKINS ETAL2,978,352

BAG TOP CLOSING AND SEALING MACHINE 5 Sheets-Sheet 5 Filed March 7, 1960il I r -g:fl-9,

FIG. 11

5 5m H mm N m t m T L mw NH mm W R WW FIG. 9

United States Frank L. Hopkins and Richard H. Ayres, Minneapolis,

Minn, assignors to Bemis Bro. Bag Company, Minneapolls, Mlnn., acorporation of Missouri Filed Mar. 7, 1960, Ser. No. 13,376

12 Claims. (Cl. 53-137) This invention relates, to newand usefulimprovements in machines for closing and sealing the open tops ofrelatively large flexible walled bags by firmly pressing the walls ofeach bag top into flatwise relation and sewing them together by a row ofstitches extending the length of the bag top and folding a strip ofsealing tape over the closed bag top walls and adhering it thereto bycoacting pressure means, as disclosed in Patent No. 2,845,- 760, grantedAugust 5, 1958.

The present invention distinguishes from the machine disclosed in theabove noted patent in that independent means is provided for pressingthe walls of the sealtape into firm contact with the bag top wallsclosely adjacent to the opposed sides of the row of stitching, therebyto prevent any possible danger of leakage in the composite bag topclosure along the row of stitching, as is possible with sewn bag tops asnow commonly constructed.

According to the present invention a thin flexible thermo-plastic coatedsealing tape is folded over the sewn bag top walls with the side wallsoverlying and concealing the row of stitches thereof in such a mannerthat when the operation of closing and sealing the bag top has beencompleted, it is unlikely that the sealed bag top will become defectiveor leaky from rough handling and treatment in transit.

Applicants have discovered that to assure the formation of a positiveleakproof closure of the type wherein the bag top walls are securedtogether by a row of chain stitching, and a strip of adhesive coatedsealing tape is then folded over the flattened bag top walls and securedthereto by passing the tape-covered bag top between a pair of co-actingpressure elements, that leakage may occur along the row of stitchingbecause of the inability of the pressure elements to press the walls ofthe sealing tape into intimate bonding engagement with the bag top Wallsin close proximity to the chain stitching.

After considerable experimental work in an effort to provide ahermetically sealed bag top closure, applicants discovered that byutilizing a thin flexible thermo-plastic coated sealing tape andpressing the walls of the sealing tape into bonding engagement with theflattened bag top 'walls by co-acting pairs of dual belt runs, the beltruns of each pair of dual belt runs being vertically spaced apart tostraddle or receive the row of chain stitching therebetween, that thebelts of each dual belt run can be so arranged that they will engage thetape walls in close proximity to the opposed sides (top and bottom) ofthe chain stitching, whereby the needle holes are positively sealedagainst leakage and thus assuring a hermetically sealed bag top closure.

An important object of the present invention, therefore, is to provideindependent pressure means for engaging each wall of the sealing tapeabove and below the row of chain stitching of the bag top, whichpressure means is heated to thereby reactivate the plastic coating onthe inner surfaces of the tape walls whereby the atent O:

. Patented Apr. 11, 1961 2 tape walls may be firmly bonded to the bagtop walls adjacent to each side of the row of chain stitching.

A further object of the invention is to provide a mechanism forpositively sealing closed bag tops after the walls of the bag tops havebeen secured together by a row of chain stitching, said mechanismincluding means for applying a strip of thermo-plastic coated sealingtape over the flattened bag top walls and folding the side wall portionsof the tape downwardly into engagement with the flattened bag top wallsand overlying and concealing the row of chain stitching, and verticallyspaced means being provided at each side of the flattened.

bag top walls for straddling the row of chain stitching and firmlypressing the tape walls above and below the row of chain stitching intofirm and intimate bonding engagement with the bag top walls closelyadjacent to the chain stitching, thereby positively sealing the needleholes against leakage and assuring a hermetically sealed closure;

A further and more specific object of the invention resides in theprovision of pairs of dual belt runs engageable with the tape walls atopposite sides of the bag top, and the belt runs of each pair of dualbelt runs being spaced apart vertically to provide a gap therebetweenfor receiving the row of stitching, and whereby the tape walls arepressed into firm contact with the walls of the bag top adjacent to eachside of the chain stitching.

A further object resides in the provision of means for heating the dualpairs of belt runs whereby the thermoplastic coating on the innersurfaces of the tape walls may be reactivated to assure an intimate bondbetween the tape walls and the bag top walls.

Other objects of the invention reside in the specific construction ofthe tape heating means which comprises one or more fixed heating barslocated at one side of the travel path of the bag tops, and a pluralityof floatingly mounted heating bars at the opposite side of said travelpath, said floatingly mounted heating bars having means for yieldablyretaining them in engagement with the dual pairs of belt runs, therebyto heat the belt runs and at the same time firmly holding them againstthe tape walls as the bag tops travel through the apparatus; thefloatingly mounted heating bars also allowing the metal belt runs toclosely follow the contour of the bag tops, when sealing the tops ofgusseted bags which are not of uniform thickness because of the intuckedend walls; and in the provision of means for automatically maintainingsaid heating bars at a predetermined temperature.

Other objects of the invention reside in the means provided for drivingthe pairs of dual belts in synchronism with the movement of the bagbodies through the machine; and in the prow'sion of a bag top sealingmechanism which is extremely simple and inexpensive to manufacture.

These and other objects of the invention and the means for theirattainment will be more apparent from the following description taken inconnection with the accompanying drawings.

In the accompanying drawings there has been disclosed a structuredesigned to carry out the various objects of the invention, but it is tobe understood that the invention is not confined to the exact featuresshown, as various changes may be made within the scope of the claimswhich follow.

In the drawings:

Figure 1 is a front elevation of the machine showing the bag tops asthey are successively fed. through the machine;

Figure (2 is a sectional plan view substantially on the line 2-2 ofFigure 1, with some of the parts omitted, showing the travel path of thebag tops, and the arrangement of the heating bars along the sidesthereof, some of the parts being broken away;

Figure 3 is a diagrammatic view showing the drive means for the dualendless steel belts and the compression rolls; 1

Figure 4 is a sectional plan view on the line 4-4 of Figure 6, on anenlarged scale, showing the stationary and theresiliently mountedheating bars, and the conductor bars for conducting heat from theheating bars to the co-acting belt runs which directly engage the tapewalls, and partially showing the means for tensioning the dual metalbelts;

Figure 5 is a cross-sectional view on the line 55 of Figure 4, showingthe vertical spacing between the dual belts of each pair of dual beltruns, thereby to accommodate the row of chain stitching therebetween,and whereby the walls of the sealing tape are pressed firmly intointimate bonding engagement with the flattened bag top walls in closeproximity to the chain stitching, and also showing the means fortensioning the dual metal belts;

Figure 6 is a cross-sectional elevation on the line 6-6 of Figure 4,showing the independent mounting of the belt-supporting pulleys at thereceiving end of the apparatus;

Figure 7 is a fragmentary view, partially broken away,

showing the means for anchoring the resiliently mounted heating barsagainst longitudinal movement;

Figure 8 is a fragmentary view on the line 8-8 of Figure 7, on anenlarged scale;

Figure 9 is a view showing the upper portion of a sealed bag top havinga sealing tape or membrane applied thereto in accordance with thepresent invention;

Figure 10 is a detail sectional view on the line 1tl-1 of Figure 9,indicating in dotted lines, how the walls of the sealing tape arepressed into firm bonding engagement with the bag top walls above andbelow the row of chain stitching by the pressure exerted on the tapewalls by the co-acting heated belt runs; and

Figure 11 is a fragmentary view, partially broken away, showing thepressure rolls at the discharge end of the apparatus for firmly pressingthe tape walls into intimate contact with the bag top walls and thechain stitching, as each bag top is discharged from the machine.

Main supporting frame The novel bag top closing and sealing mechanismherein disclosed comprises an elongated main supporting frame 2, shownhaving a mounting plate 3 at one end to facilitate attaching it to a bagtop sewing mechanism, not shown .in the drawings, such as shown inFigures 1 and 3 of Patent No. 2,845,760. The frame comprises ahorizontal wall portion 4 and a rear upright wall portion 5 whichcooperate to form an angular frame section, as best illustrated inFigure 5.

The'main supporting frame also comprises an elongated front angularframe section 6 secured to the rear frame section 2 by laterallydisposed frame sections 7 and 8 at the front and rear ends ofthe frame,respectively, and intermediate cross members 9 and 11, best illustratedin Figure 2. The bag top closing and sealing mechanism herein discloseddistinguishes from the machine disclosed in theabove mentioned patent inthe means provided for pressing the tape walls into bonding engagementwith the flattened bag top walls.

Tape applying mechanism Heretofore, co-acting single belt runs have beenutilized for pressing the walls of a sealing tape into engagement withthe bag top walls. This method of pressing the sealing tape intoengagement with the bag top walls has not proven entirely satisfactorybecause when utilizing only'a single belt run at each side of the bagtop, the needle holes of the chain stitching are not completely sealedadjacent to the row of stitching because of the inability of such beltruns (usually rubber) pressing the tape walls into firm bondingengagement with the bag top walls in close proximity to the opposedsides of the chain stitching with suflicient pressure to assure aleaktight connection between the tape walls and the bag top walls alongthese areas. In such known equipment the actual sealing of the tapewalls to the walls of the bag top is accomplished by a pair ofrubber-faced pressure rolls between which each bag top must pass as itleaves the rubber belts.

To thus press the walls of the sealing tape into engagement with the bagtop walls closely adjacent to the opposite sides of the chain stitching,dual belts l2 and 13 are provided at each side of the travel path of thebag tops, as best illustrated in Figures 1, 8 and 10. These belts arepreferably constructed of flexible band metal and are supported at thereceiving end of the machine upon independently mounted pulleys 14 and15. These pulleys are independently adjustable to maintain the endlessbelts 12 and 1.3 at the proper operating tension, as will subsequentlybe described.

Belt supporting and drive means At the discharge end of the machine theendless belts 12 and 13 are supported upon drive pulleys 16, secured tothe lower ends of upright shafts 17 and 17 mounted in suitable uprightbearings 18 forming a part of the main supporting frame. Secured to theupper ends of shafts 17 and 17 are a pair of spur gears 19 and 19,respectively, which mesh with one another to cause the shafts 17 and 17'to rotate in opposite directions, as indi cated by the arrows in Figure3. A sprocket wheel 21 is secured to shaft 17 directly above spur gear19, and has a driving connection with a drive chain 2 2, the oppositeend of which is connected to a source of power, subsequently to bedescribed.

A second sprocket wheel 23 is secured to shaft 17 above sprocket wheel21, and has a chain 24 connecting it to a sprocket wheel 25 secured tothe upper end of a shaft 26, mounted in a bearing 27 of the main frame.A pressure roll 28 is secured to the lower end of shaft 26 andcooperates with a similar roll 29 to impart a final squeezing action toeach bag top as it is discharged from the machine. Annular resilientinserts 31 are seated in annular grooves provided in the peripheries ofpressure rolls 2% and 2h, and are located at an elevation to engage andpress the sealing tape into intimate bondingengagement with the chainstitching, as is best illustrated in Figure 11.

Roller 29 is secured to the lower end of a shaft 32 rotatably mounted ina bearing member 33 having laterally extending arms 34 and 35 bored toreceive the end portions of a stub shaft 36, secured in a hub 37 of themachine frame. A set screw 38 secures the stub shaft 36 against axialand rotary movementsin the hub 37. The upper ends of shafts 26 and 32are operatively connected together by a pair of spur gears 39 and 41,respectively, as indicated in-Figures l and 3, whereby the pressurerolls 28 and 29 are rotated in opposite directions, as indicated by thearrows in Figure 3.

Pressure rolls 28 and 29 are yieldably held in engagement with theflattened tape-covering bag top, as shown in Figures 2 and 11, by atension rod 42 having one end secured in a lug 43 provided on thebearing member 27 of shaft 26, as clearly illustrated in Figure 2. Theopposite end portion of rod 42 is slidably received in a lug 44 securedto hearing member =33 of shaft 32, and has a spring 45 coiled about oneend portion thereof, one end of which is seated against lug 44, and itsopposite end against a washer-and-nut combination 46, whereby the springmay be tensioned to constantly urge roller 2 in a direction towardsroller 23. The pressure exerted upon the bag top by rollers 28 and 29may be varied as desired by manipulation of nut 46.

The means for driving the dual belts 12 and 13 and the pressure rolls 2%and 29 is best illustrated in Figure l, and comprises a speed reducer 47having a shaft 48 to which is secured a V-pulley 49 having a V-belt 51connecting it to a suitable source of power such as an electric motor,not shown in the drawings. The speed reducer has a depending speedreduction shaft 52 to the lower end of which a sprocket wheel 53 issecured. Sprocket 53 has a driving connection with chain 22, as will benoted by reference to Figure l. A chain tightener, generally indi catedat 54, is adjustably mounted on a bracket 55 secured to the upright wallportion 5 of the main supporting frame, as indicated at 56 in Figure 1.Sprocket 54 provides means for maintaining chain 22 at the properoperating tension.

Mounted on shaft 52 directly above sprocket 53 is a similar sprocket '57having a chain 58 connecting it to a sprocket wheel 59 secured to theupper end of a shaft 61. Secured to the lower end of shaft 61 is a bagtop feed roll 62 which cooperates with a similar roll 63, indicated inFigure 2, to successively feed the bag tops from the tape folder 64,partially indicated in Figures 1 and 2, to the dual belt runs 12 and 13,as will be understood by reference to Figures 1 and 2.

Suitable means, not shown, is provided for supporting a roll of tapeover the machine and guiding it into the tape folder 64-. Such amechanism is shown and described in Patent No. 2,845,760, and it istherefore believed unnecessary to herein describe said mechanism indetail. The bag top feed rolls 62 and 63 are interconnected by a pair ofspur gears 65, indicated in Figure 1. A tape clipper, generallyindicated by the numeral 50, is shown in Figurel for clipping the tapebetween bag tops, as the bag tops are successively fed along between thedual pairs of belt runs 12 and 1 3.

Dual belt tensioning means Another important feature of the inventionresides in the means provided for maintaining the dual belt runs 12 and13 at the proper operating tension. Such a tensioning means isillustrated in Figures 4, 5 and 6. It c0m prises a pair of tension rods66 and 67. The upper tension rod 66 is shown having one end pivoted toan arm 60 secured to the upper end ofa shaft 68, mounted for rockingmovement in a bearing 69 in the machine frame, as best illustrated inFigure 6. Shaft 68 has an arm 71 secured to its lower end by a pin 72.Arm 71 is disposed in right angular relation to arm 60 at the upper endof shaft 63 and has a stud 73 secured thereto which rotatably supportspulley 14.

Pulley 14 at the front side of the machine is supported on a stud 74having its upper end secured in an arm 75, as indicated at 76 in Figure6. Arm 75 is secured to the lower end of a shaft 77 having an arm '78secured to its upper end by suitable means, such as a set screw 79.Tension rod '66 has one end pivoted to arm 60, as indicated at 81 inFigure 5. The opposite end portion of rod 66 is slidably received in aguide 82 pivoted to arm 78, as will be understood by reference to Figure5. A spring 83 is coiled about rod 66 and has one end seated againstguide 82 and its opposite end against an adjusting nut 84 received inthreaded engagement with rod 66, whereby arms 71 and 75 are constantlyurged in a direction to tension co-acting belt runs 12-12.

The lower co-acting belt runs 13-13 are maintained at the properoperating tension by the tension rod 67, one end of which is pivoted toan arm 85 by a pivot pin or stud 86. The opposite end of rod 67 isslidably sup ported in a guide 87 and has a spring 88 coiled thereabout,one end of which is seated against guide 87 and its opposite end againstan adjusting nut '89, secured to the threaded end portion of rod 67, asshown in Figure 5.

Guide 87 is pivoted to an arm 91 secured to a hub 92 mounted for pivotalmovement on a sleeve 93, bored to receive a bolt 94 having its upper endreceived in threaded engagement with the machine frame, as indicated at95 in Figure 6. A washer 96 is positioned between the bottom end of thesleeve 93 and the head of bolt 94,

G. whereby the sleeve may be non-rotatably secured in position so thatthe hub may rotate freely on the sleeve 93, as will be understood byreference to Figure 6. It is to be understood that the sleeve 93 isslightly longer than the hub 92, thereby to permit the hub to rotatefreely on the sleeve 93 without binding.

The hub 92 has an arm 97 at its lower end disposed in right angularrelation to the arm 91 at its upper end. Pulleys 15-15 are rotatably'supported at the outer ends of arms 97 and 98 by pivot pins or studs 99,as best illustrated in Figure 6. Suitable anti-friction bearings may beprovided for supporting pulleys 14 and 15 upon their respective studs.Arm 98 is secured to a hub 101 in a manner similar to the way arm 97 issecured to hub 92. Ann 85, as shown in Figures 5 and 6, is secured tothe- Belt heating means Another important feature of the presentinvention resides in the arrangement of the dual metallic belts 12 and13 and the means provided for heating them to cause the plastic coatingon the tape to become reactivated so that the tape walls may beintimately bonded to the bag top walls, as the bag tops successivelypass through the bag top sealing mechanism.

To thus heat the dual belt runs, a plurality of heating bars areprovided. Two such heating bars 102 and 103 are shown arranged inend-to-end relation at one side of the travel path of the bags, and fourrelatively shorter heating bars 104, 105, 106 and 107 are similarlyarranged at the opposite or front side of the travel path, as bestillustrated in Figure 2. Heating bars 102 and 103 are fixedly secured tothe main supporting frame by suitable bolts 108, received in aperturesprovided in the supporting frame and having their lower .threadedterminals shown received in threaded engagement with the heating bars102 and 103, as best illustrated in Figure 5.

Spacers 109 are interposed between heating bars 102 and 103 and the mainsupporting frame, as indicated in Figures 5 and 7. The lower ends ofspacers 109 are preferably beveled at opposite sides, as shown at 111 inFigure 7, to reduce the transmission of heat from the heating bars 102and 103 to the main frame. Each heat ing bar 102 and 103 has aheat-conducting plate or bar 112 secured to its inner face by bolts orscrews 110. Heat-conducting bars 112 are longitudinally grooved, asshown at 113 in Figure 8 to permit free passage of the chain stitchingat one side of the bag top, as will be understood by reference to Figure8. The relatively shorter heating bars 104, 105, 106 and 107 aresimilarly provided with heat-conducting bars 114 secured to theirrespective heating bars by bolts 115. Said heat-conducting bars arelongitudinally grooved, as at 129, shown in Figure 8, to clear the chainstitching at the front side of the bag tops,

To yieldably hold the heating bars 104, 105, 106 and 107 against thebelt runs, said heating bars are mounted for independent movement sothat they may yield to any irregularities occurring in the bag topwalls, as the bag tops pass through the machine. Each of the relativelyshorter heating bars at the front side of the travel path of the bagtops is shown having two shouldered studs ,116 secured thereto whichproject laterally therefrom Secured in threaded engagement with theouter end portion of each stud 116 is a nut 123, shown in Figure 4'.Nuts 123 are adjustably secured to the terminals of their respectivestuds 116, and provide seats for the forked terminals 124 of a pluralityof flat spring elements 125, best illustrated in Figures 2 and 4. Theintermediate portion of each spring element 125 is apertu-red to receivean adjusting screw 126 having its threaded end portion received inthreaded engagement with the composite supporting bar or member 118, aswill be understood by reference to Figure 4. The nuts 123 of studs 116engage the forked end portions of the resilient elements 125 wherebysaid elements 125 constantly urge heating bars 104, 105, 106 and 107 ina direction towards the tape walls. Manipulation of adjusting screws 126will vary the inward pressure of the movable heating bars against thedual belt runs 12 and 13, as will be understood.

Supporting bar 118 may be constructed of a plurality of flat members a,b and c, secured together in flatwise relation by the bolts 119 and aplurality of screws 121}, indicated in dotted lines in Figure 8. Membersa and c extend the full length of the composite member or bar 118,whereas the intermediate members b are relatively shorter and serve asspacers between the top and bottom members a and c. It will also benoted that the intermediate members b have their ends spaced apart toprovide the openings 1'17 for the studs 116. See Figures 7 and 8. Ifdesired, supporting member 11-5 may be otherwise constructed as, forexample, it may be formed from a single piece of bar stock in which casethe openings 117 for the studs 116 would be drilled.

A spacer 128 is provided on each stud 116 between its nut 123 and thecomposite supporting bar 118 for limiting the inward movement of theheating bars, in the event such movement is to be limited. Each heatingbar 104, 105, 106 and 107 has a heat conducting bar on plate 114 securedthereto by bolts 115, as will be understood by reference to Figure 8.From the foregoing, it will be noted that when the heating bars aresecured in their respective positions in the machine frame, the opposedlongitudinally extending grooves 113 and 129 in their respective heatconducting bars will permit free passage of the chain stitching betweenthe heat conducting bars as the flattened bag tops are fed through themachine. It will also be noted that the dual pairs of belt runs 1213 and12-13 at opposite sides of the travel path of the bag tops will engagethe tape walls closely adjacent to the chain stitching, whereby the tapewalls are pressed firmly into intimate bonding engagement with the bagtop walls in close proximity to the chain stitching, whereby the needleholes are positively sealed against leakage.

- Means is provided for restraining the resiliently and floatinglymounted heating bars 104, 105, 1% and 197 against relative longitudinalmovement in the machine frame, and is shown comprising a plurality ofconnecting links 132, 1135, 134 and 135, shown in Figures 1 and 7.Connecting links 132 and 133 each have one end pivotally connected to acommon anchor pin 136, mounted in a bracket 137 secured to thesupporting member 118 by suitable means such as welding. The oppositeends of links 132 and 133 are pivotally connected to their respectiveheating elements 104 and 105 by pivot pins 1139.

Belt cleaning elements 140 are prefenably provided for cleaning themetallic belts, as indicated on Figures 1, 2, and 4.

Heating bars 106 and 107 are similarly restrained against relativelongitudinal movement by links 134 and 135, each having one endpivotally connected to a common anchor'stud 141 mounted in a bracket 142secured to member 118, in a manner similar to heating bars 104 and 105.

Heating bars 102 and 107, inclusive, are electrically heated by suitableresistance elements, not shown in the nated' by the numeral 147,connected to a source of electric power, not shown.

Heating bars 104, 105, 106, and 107 are shown having conduits 148,149,151 and 152, respectively, electrically connecting them to ajunction box 153 which, in turn, is electrically connected to thecontrol box 14-7 by a conduit 154. The two banks of heating bars arethermostatically controlled by suitable thermostats, indicated 155 and156. The electrical system shown in Figure l is well known in the art,and it is therefore deemed unnecessary herein to describe the same indetail.

As hereinbefore stated, the present invention is not concerned with thesewing of the bag top walls. Its primary purpose is to provide means forhermetically sealing the bag tops as the bag tops are successively fedthrough the machine. This is accomplished by applying a thin, flexible,plastic coated strip of sealing tape over each sewn bag top and pressingthe side wall portions thereof into firm bonding engagement with the bagtop walls closely adjacent to the opposite sides of the stitching andsecuring said tape wall portions thereto by the application of heat andpressure, whereby the bag tops are positively sealed against leakage,even when roughly handled in transit.

The novel bag top sealing mechanism herein disclosed has been foundextremely practical and eflicient in actual operation. By applying astrip of thermoplastic coated tape over the sewn bag top walls andbonding it thereto by the use ofthe dual heated belt runs, one belt runengaging the tape walls above the chain stitching, and the otherdirectly below the chain stitching, the tape walls 'may be pressed intointimate bonding engagement with the bag top Walls close to the row ofstitching, which is of utmost importance to eifect a positive seal.After thus bonding the tape walls to the bag top walls, the portions ofthe tape which overly the chain stitching are pressed firmly against thestitching and bag top walls by the compression rolls 28 and 29 therebyto complete the closing and sealing of the bag tops.

It is apparent that many modifications and variations of the inventionas hereinbefore set forth may be made without departing from the spiritand scope thereof. The specific embodiments described are given by wayof example only and the invention is limited only by the terms of theappended claims.

We claim as our invention:

1. In an apparatus for applying a strip of thermoplastic coated tapeover the upper marginal edge portions of the walls of a bag top whosewalls have previously been secured together in flatwise relation by arow of chain stitching extending the length of the bag top, means forguiding a strip of sealing tape over the top edge of each sewn bag topand folding the side wall portions thereof downwardly into flatwiseengagement with the opposed wall surfaces of the bag top and whereby thetape overlays and conceals the chain stitching, pairs of dual belt runscooperating to form a travel path for the bag tops, the belt runs ofeach pair of dual belt runs being vertically spaced apart to receive thechain stitching therebetween, heating means for pressing the belt runsof each pair of dual belt runs into engagement with the tape wallsclosely adjacent to the opposite sides of the chain stitching, therebyto heat and reactivate the tape walls and cause them to becomeintimately bonded to the bag top walls.

2. An apparatus according to claim 1 wherein means is provided forcontrolling the temperature of the heating means.

3. In an apparatus for applying a strip of thermoplastic tape over theupper marginal edge portions of the walls of a closed bag top whosewalls have previously been secured together in flatwise relation by arow of chain stitching extending the length of the bag top, means forguiding the tape over the top edge of each sewn bag top and folding theside portions thereof downwardly into fiatwise engagement with theopposed wall surfaces of the bag top and whereby the tape walls overlayand conceal the chain stitching, co-acting pairs of dual beltscooperating to form a travel path for the bag tops, means at each end ofthe apparatus for supporting said pairs of dual belts whereby the beltsof each pair of dual belts are vertically spaced apart to provide gapstherebetween for receiving the chain stitching, heating bars at eachside of said travel path, and resilient means for pressing the heatingbars at one side of said travel path into heating engagement with theirrespective belt runs.

4. In an apparatus for sealing a sewn bag top against leakage, asupporting frame, two pairs of single pulleys at the receiving end ofthe machine and a pair of dual pulleys at the discharge end of themachine, a plurality of endless metallic belts mounted on said pulleysand having certain runs thereof disposed in contiguous relation andcooperating to form a travel path for the bag tops to be sealed, meansfor folding a strip of sealing tape over each flattened bag top, thebelts at each side of said travel path being arranged in pairs with thebelts of each pair being vertically spaced apart to receive therebetweenthe chain stitching of each bag top, a plurality of heating bars forheating the belt runs forming said travel path, said heated belt runssoftening and reactivating the thermoplastic coating on said tape, andresilient means for constantly urging said heated belt runs intoengagement with the tape walls closely adjacent to the stitchingthereof, whereby all needle holes in the bag top walls are hermeticallysealed.

5. In an apparatus according to claim 4, wherein the pulleys of eachpair of single pulleys at the receiving end of the apparatus are mountedfor independent adjustment.

6. In an apparatus according to claim 5, wherein the corresponding beltsat each side of the travel path of the bag tops are tensioned by a belttensioning device which is common to said corresponding belts, therebyto assure uniform tension in said belts.

7. In an apparatus according to claim 6, wherein means is provided atthe discharge ends of said belts for receiving and applying a finalsqueezing action to the sealed bag tops, thereby to press the tape wallsfirmly into bonding engagement with the bag top walls and the chainstitching, thereby to hermetically seal each bag top closure againstleakage.

8. In an apparatus according to claim 5, wherein the vertically spacedpulleys of each pair of single pulleys at the receiving end of theapparatus are mounted for swinging movement in a horizontal plane aboutvertical axes, and means for independently tensioning the beltssupported on said vertically spaced pulleys.

9. In an apparatus for hermetically sealing a closed bag top whose wallshave previously been secured together in fiatwise relation by a row ofstitching extending the length of the bag top, means for applying aflexible sealing element over the flattened bag top walls and foldingthe side wall portions thereof downwardly into engagement with theopposed wall surfaces of the bag top and over the row of stitching, apair of dual belt runs on each side of the bag top, the belt runs ofeach pair of dual belts being vertically spaced apart to receive the rowof stitching therebetween, and means for simultaneously pressing saiddual belt runs into engagement with the walls of the sealing elementclosely adjacent to the row of stitching, thereby to intimately bond thewalls of the sealing element to the bag top walls adjacent to thestitching to positively prevent leakage of the contents from the bagbody through the needle holes of the stitching.

10. An apparatus according to claim 9, wherein a plurality ofindependently mounted heating elements are provided for yieldablyretaining the dual belt runs in engagement with the walls of the sealingelement, and whereby the belt runs may follow the contour of the bag topwalls as the bags pass through the apparatus.

11. An apparatus according to claim 10, wherein the heating means forthe belt runs comprises an elongated fixed heating bar located at oneside of the travel path of the bag tops and a plurality of relativelyshorter heating bars arranged in end-to-end relation at the oppositeside of said travel path, said heating bars cooperating to press theheated belt runs into intimate engagement with the walls of the sealingelement directly above and below the row of stitching.

12. In an apparatus for hermetically sealing a closed bag top whosewalls have previously been secured together in flatwise relation by arow of stitching extending the length of the bag top, means for applyinga flexible sealing element over the flattened bag top walls and foldingthe side wall portions thereof downwardly into engagement with theopposed wall surfaces of the bag top and over the row of stitching, anelongated fixed heating bar located at one side of the travel path ofthe bag tops, and a plurality of independently mounted relativelyshorter heating bars arranged in end-to-end relation at the oppositeside of said travel path, said shorter heating bars yieldably retainingthe dual belt runs in engagement with the walls of the sealing elementpermitting said dual belt runs to follow the contour of the bag topwalls directly above and below the row of stitching, as the bags passthrough the apparatus.

References Cited in the file of this patent UNITED STATES PATENTS2,097,449 Cundall Nov. 2, 1937 2,362,462 Belcher Nov. 14, 1944 2,447,014Irmscher Aug. 17, 1948 2,845,760 Hopkins Aug. 5, 1958

